I did ask this question on someone elses post last night but nobody responded so here it is again :)

In my bettas tank I have black gravel which is quite rough, I am thinking about replacing it with some black sand but can't find any at a reasonable price, I did however find Exo Terra black sand on a website I use and was wondering whether this would be suitable for my betta? It is meant for reptiles/amphibians so the only thing I can think of would be that it may have calcium but the site doesn't say, so I was wondering whether anyone has used it before for a fish and if it is suitable?

Heres the link for the sand, just in case your not familiar with it :)

Nope, they're intended for freshwater tanks only. I use Eco Complete and Flourite black sand in my planted tanks since it is enriched with nutients. Tahitian Moon Sand is neutral and can be used in either marine or freshwater aquariums.